Method and apparatus for automatic implantable medical lead recognition and configuration

ABSTRACT

An automated identification and configuration system for use with an implantable medical device (IMD) is disclosed. The system includes a first communication circuit that is attached to, or otherwise carried by, a detachable component associated with the IMD such as a medical lead. The communication circuit stores data such as model numbers, serial numbers, technical data, and/or calibration information that describes the additional component. This information may be transferred by the first communications circuit to a second communications circuit that is external to the additional component. This transferred data can be used to automatically configure the internal circuitry and connection functions of the IMD to properly interface with, and support, the additional component. For example, the data can be used to automatically adjust amplifier gains or other sensor circuitry, or to configure a connector block to properly couple to the component. The data may further be entered into a patient record on an external programmer, or may be transferred to a central storage location to be generally accessible to health care providers. In one embodiment, the first communication circuit is a passive RF transponder. This first communication circuit may include a receiver as well as a transmitter to allow the circuit to programmably receive data at the time of component manufacture.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to implantable medical devices;and, more particularly, to a method and apparatus to automaticallyidentify multiple leads and their proper connection to an implantablemedical device such as a pacemaker or cardioverter/defibrillator.

2. Background Art

An implantable intravascular lead assembly is often implanted within apatient's body to provide electrical stimulation to the heart. Such leadassemblies may include one or more electrical conductors that areadapted to be suitably connected to a source of electrical energy, whichmay be a pacemaker or cardioverter/defibrillator. The electricalconductor, in turn, includes an electrode tip that engages theendocardial or epicardial tissue of the heart to provide stimulation andsensing capabilities. The lead assembly may be intravenously insertedthrough a body vessel, such as a vein, into one or more cardiacchambers, or alternatively, attached to the epicardial surface of theheart. The conductor is sealed from body fluids by a biocompatible andbio-stable insulating material.

In a typical lead assembly, the electrode tip is firmly lodged in, andpermanently secured to, the endothelial lining or epicardial surface ofthe heart. These lead assemblies are referred to as an endocardial orepicardial lead, respectively. Some examples of conventional endocardialand epicardial leads may be found in U.S. Pat. No. 3,348,548 toChardack, U.S. Pat. No. 3,754,555 to Schmitt, U.S. Pat. No. 3,814,104 toIrnich et al., U.S. Pat. No. 3,844,292 to Bolduc, U.S. Pat. No.3,974,834 to Kane, U.S. Pat. No. 5,246,014 to Williams, and U.S. Pat.No. 5,397,343 to Smits. A representative defibrillation lead isdescribed in U.S. Pat. No. 6,178,355 to Williams.

With the increased use of multi-chamber pacemakers and defibrillatorssuch as those that provide bi-atrial or bi-ventricular pacingcapabilities, multiple leads are required to deliver electricalstimulation to various locations within the heart. With the use ofmultiple leads that are positioned within one or more small vessels ofthe body, it has become even more important to minimize lead and leadconnector size. As leads become smaller, it becomes increasinglydifficult to mark leads with the appropriate identification, includingmanufacturer identification and/or lead model and serial numbers. Thismay make it more difficult for a physician to determine which lead is tobe inserted into a given port of an implantable medical device (IMD)during an implant procedure.

One solution to providing marking information on lead systems isdescribed in U.S. Pat. No. 5,824,030 to Yang. This patent discloses asingle-pass transvenous lead for atrial sensing and pacing, ventricularsensing and pacing, as well as for ventricular and atrialdefibrillation. Visual indicators are provided on the lead to identifywhich one of several distal electrode pairs are being used.

Another solution to properly configuring the leads of an IMD isdisclosed in U.S. Pat. No. 5,374,279 to Duffin. The described medicalelectrical pulse generator includes a switchable connector assembly. Theconnector assembly is provided with connector bores that are eachadapted to receive a medical electrical lead. Electrical connectorslocated within the bores are arranged such that interconnection of thepulse generator circuitry and the configuration of the electrodes on theleads and/or housing of the device can be altered by means of connectorpins.

Yet another method of attaching multiple electrode leads to an IMD isdescribed in U.S. Pat. No. 4,628,934 to Pohndorf. The '934 patentdescribes an electronic electrode switching circuit that minimizes thenumber of feedthroughs from a pacer case to a pacer neck that are neededto couple to the pacing lead electrodes. These feedthroughs can beselectively connected to a desired electrode by the physician at thetime of initial implantation or any time thereafter. The electronicconnection to a feedthrough may be dedicated to a single electrode orelectrode pair, or alternatively, the electrodes may be electronicallysampled by circuitry in the pacer. The electrode switching circuit maybe located in the pacer neck, in an adapter between the pacer neck and amultielectrode lead, or in a multielectrode lead.

Another method for automatically configuring the multiple leads of anIMD is described in U.S. Pat. No. 6,085,118 to Hirschberg. The '118patent describes an implantable cardiac stimulator with at least twoterminals. Each terminal is connectable to an implantable electrode fordelivering stimulation pulses to a heart, and/or for sensing cardiacactivity signals. The stimulator also has a switch and a control unitwhich operates the switch, so that one or both terminals are connectableto the pulse generator. The control unit identifies a position statusfor at least one of the electrodes in response to a signal received atthe time of implantation. Although the control unit may use a signalfrom an electrode to configure the switch, premature sensed events,artifacts and/or EMI may cause the control unit to incorrectly configurethe system.

Another identification system is described in U.S. Pat. No. 5,300,120 toKnapp, which involves a passive transponder that may be encoded with abinary value that may be up to sixty-four bits long. This value may beread with a hand-held electromagnetic device that is located outside thebody and in proximity to the transponder. The encoded information mayinclude patient demographics, implant data, and manufacturerinformation.

Another similar mechanism for remotely monitoring device data isdescribed in U.S. Pat. No. 5,626,630 to Markowitz. The disclosedtelemetry system includes a remote monitoring station, a repeater wornexternally by a patient, and a quasipassive transponder attached to adevice implanted in the patient. The remote monitoring stationcommunicates to the repeater to initiate an interrogation routinebetween the repeater and the transponder to extract patient conditioninformation from the implanted device. When the repeater receives thecondition information, it relays it to the remote monitoring station.The disclosed system does not automatically identify leads, calibratelead-based sensors, or automatically configure leads and/or sensors toan IMD.

U.S. Pat. No. 5,833,603 to Kovacs describes another system for sensingone or more physiological signals within a living body to measureoptical, mechanical, chemical, and/or electrochemical properties. Thesystem includes a transponder for wirelessly transmitting datacorresponding to the sensed parameter values to a remote reader.Disclosed embodiments utilize temperature sensors, strain sensors,pressure sensors, magnetic sensors, acceleration sensors, ionizingradiation sensors, acoustic wave sensors, chemical sensors, andphotosensors. The disclosed system does not include means toautomatically identify or configure leads, or to calibrate thelead-based sensors.

Another mechanism for identifying information related to theconfiguration of an IMD is disclosed in U.S. Pat. No. 5,423,334 toJordan. The disclosed system provides a characterization tag forattachment to the IMD. The tag circuitry is selectively loaded to storedata describing the IMD, and may be read by a probe located outside thebody. The system does not store lead identification or configurationinformation.

Yet another system for storing and transmitting device information isdescribed in U.S. Pat. No. 5,252,962 to Urbas. The disclosed deviceincludes a sensor for use in transmitting a parameter such astemperature from within a living body to a device that is locatedoutside the body. The IMD includes a programmable memory to store userID data.

While the above publications teach various improvements to the art, theydo not address the problem of identifying and configuring multiple leadsand/or other implantable devices for use with an IMD.

SUMMARY OF THE INVENTION

It is a principal object of the present invention to provide an improvedinterface between conventional lead systems and IMDs.

Another object is to provide a system and method for automaticallyidentifying leads and for enabling the proper connection of theidentified leads to an IMD.

Another object is to provide a system and method for automaticallyreceiving sensor calibration information for lead-based sensors.

Yet another object is to provide a system and method for automaticallycalibrating lead-based sensors.

Another object is to provide an IMD that automatically configuresconnections between one or more leads and respective IMD ports.

An additional object is to provide a connector block for electricallyand mechanically coupling multiple leads or sensors to an electricalsource of energy, such as a pacemaker, defibrillator or neurostimulator.

Yet another object is to provide a system for use with an IMD thatallows an additional component of the IMD to be automatically identifiedfor purposes of system configuration.

It is a further object to provide a system for use with an IMD thatstores patient data that may be transferred to a central location foruse in performing diagnosis and therapy.

The current system and method addresses these and other objectives byproviding a system for use with an active IMD (hereinafter, “IMD”) suchas a pacing device, or another external device. The system is capable ofautomatically identifying one or more additional implantable medicaldevices such as leads that may be associated with the IMD. In oneembodiment, the invention includes a first communication circuit that isattached to, or integrated within, a lead. The communication circuitstores data such as model and serial numbers, technical information, andcalibration data. At the time of implant or sometime thereafter,information stored by the first communication circuit may be transferredto a second communications circuit that is external to the lead. Thesecond communications circuit may reside within the IMD, an externalprogrammer, a personal data management (PDM) unit, or within any otherunit such as a Personal Digital Assistant (PDA) that is located within apredetermined range of the first communication circuit. This transferreddata can be used both to indicate the presence of the lead, and toidentify lead type. Such information can be used, for example, toautomatically configure the connector block of the IMD to properlycouple to the lead. The data can further be used to automatically adjustamplifier gains or other circuitry associated with the lead. The datamay be entered into a patient record on an external programmer, or maybe transferred to a central storage location for use by health careproviders when performing diagnosis and therapy associated with the IMD.

In another embodiment, the data provided by the first communicationscircuit includes identification and calibration information concerningadditional components of the system. For example, physiologic sensorscarried on the leads may be identified so that the IMD can enable andcalibrate internal circuitry to receive the physiologic signals. Thisallows certain functions within the IMD to automatically be enabled onlywhen a component is present in the system so that power can otherwise beconserved. Any other components of an IMD may be identified andcalibrated by using a communication circuit according to the currentinvention. This may include implantable devices such as pluggableantennas, electrodes that can be selectively coupled to the IMD case,and any other types of components that may be selectively added to thesystem.

According to one aspect of the system, the first communication circuitmay be a passively-powered RF transponder. The transponder receivespower from an external source. Ultrasonic, optical, and electromagneticpower may be used to power the first communication circuit. In anotherembodiment, the first communication circuit may receive power from itshost unit, such as via the conductors of a lead. According to anotheraspect of the system, the first communication circuit may include areceiver as well as a transmitter to receive data signals from anexternal source. This allows the first communication circuit to beprogrammed with identification, calibration, and other data at the timeof component manufacture.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of an implantable medical device (IMD)implanted within a body.

FIG. 2 is a side cutaway view of an exemplary in-line connector assemblyat line 2—2 of FIG. 1

FIG. 3 is a side perspective view of one embodiment of passivetransponder of FIG. 2.

FIG. 4 is a side perspective view illustrating a sealed transpondercoupled to a lead.

FIG. 5 is a system block diagram of one embodiment of an IMD that mayutilize the current invention.

FIG. 6 is a circuit block diagram illustrating in more detail exemplarycomponents of the transponder and transmitter/receiver circuit of FIG.5.

FIG. 7 is a system block diagram illustrating additional embodiments ofthe present invention.

FIG. 8 is a circuit diagram illustrating a transponder coupled to thetherapy output energy source of an IMD.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 is a schematic view of an implantable medical device (IMD) 12implanted within a body. Leads 14 and 15 are shown coupled to theconnector assembly 20 of IMD 12 using one or more feedthroughs. IMD 12,which may be implanted near a human heart 16 or at another location inthe body, may be a pacemaker, cardioverter/defibrillator, drug deliverydevice, brain stimulator, gastric stimulator, nerve stimulator, or anyother implantable device. For example, implantable medical device 12 maybe an implantable cardiac pacemaker such as that described in U.S. Pat.No. 5,158,078 to Bennett et al., U.S. Pat. No. 5,312,453 to Shelton etal., or U.S. Pat. No. 5,144,949 to Olson et al. Alternatively, IMD 12may be a pacemaker-cardioverter-defibrillator (PCD) such as thosedescribed in U.S. Pat. No. 5,545,186 to Olson et al., U.S. Pat. No.5,354,316 to Keimel, U.S. Pat. No. 5,314,430 to Bardy, U.S. Pat. No.5,131,388 to Pless, or U.S. Pat. No. 4,821,723 to Baker, et al. As yetanother example, IMD 12 may be an implantable neurostimulator or musclestimulator such as those disclosed in U.S. Pat. No. 5,199,428 to Obel etal., U.S. Pat. No. 5,207,218 to Carpentier et al., or U.S. Pat. No.5,330,507 to Schwartz. The IMD may also be an implantable monitoringdevice such as that disclosed in U.S. Pat. No. 5,331,966 to Bennett etal., wherein all of the foregoing patents are incorporated by referenceherein in their respective entireties.

FIG. 2 is a side cutaway view of an exemplary in-line connector assembly20 at line 2—2 of FIG. 1. The connector assembly is shown coupled to aproximal end of lead 14. Connector assembly 20 employs a “setscrewless”lead retainer, and a stepped lumen 202 that receives a connector pinmounted to the proximal end of lead 14. The connector pin includes twoconductive connector surfaces 208 and 210, and two insulative areas 212and 214. Insulative areas 212 and 214 are each provided with a pluralityof sealing rings 218 and 220 to seal lumen 202 against fluid entry andto provide a seal intermediate conductive areas 208 and 210. Conductivearea 208 may take the form of a metallic, cylindrical pin. Conductivearea 210 is illustrated as a metal cylinder.

Connector assembly 20 is shown mounted to the outer enclosure 222 of IMD12. Connection between the implantable pacemaker and the lead 14 is madeby means of spring members 224 and 226, which are mounted in conductiveferrules 228 and 230, respectively. Ferrules 228 and 230 are metalcylinders having central bores and associated internal circumferentialgrooves that retain the spring members 224 and 226. When inserted,spring members 224 and 226 provide for electrical coupling. Ferrules 228and 230 are coupled to feedthrough wires 232 and 234 by means of wires236 and 238, respectively.

The proximal end of lead 14 is shown provided with a cylindrical plasticmember 240 that includes a circumferential groove 242 that mates with adeflectable beam lead retainer 244 provided at the distal end of theconnector assembly 20. In the embodiment shown, the lead retainer 244 isintegrally molded to connector module 20, although the retainer may alsobe fabricated separately. Surrounding the deflectable lead retainer 244is an insulative boot 246, which in turn, is surrounded by a suture 248that acts as a lock to prevent expansion of the deflectable beamretainer 244 to retain lead 14 within connector assembly 20.

The proximal end of lead 14 further includes a first and secondcommunication circuit, which in this embodiment are a passivetransponder 262 adapted to communicate with transmitter/receiver 260,respectively. This communication may be facilitated by RF transmissionsas substantially described in U.S. Pat. Nos. 4,730,188, 5,041,826, and5,166,676 to Milheiser, U.S. Pat. No. 5,025,550 to Zirbes, or U.S. Pat.Nos. 5,223,851 and 5,281,855 to Hadden, incorporated herein by referencein their entireties. As noted in the foregoing patents, such passivetransponders include an energy coupler for wirelessly couplingelectromagnetic, ultrasonic, or optical energy, for example, that isprovided by a remote energy source. In one embodiment of the currentinvention, the energy source is provided by transmitter/receiver 260.Energy may also be provided by another circuit in the IMD. Passivetransponder 262 further includes a communication circuit powered by theenergy received from the remote energy source, and that is adapted totransfer a signal indicative of identification data stored within thetransponder. This will be discussed further below.

It may be noted that the connector assembly 20 shown in FIG. 2 isexemplary only, and many other types of connector assemblies and leadconnector types including in-line or bifurcated lead connectors andconnector assembly configurations may be utilized.

FIG. 3 is a side perspective view of one embodiment of passivetransponder 262 of FIG. 2. The transponder includes a wire coil antenna106 encircling bobbin 108. This antenna may be tuned to the frequency ofthe carrier signal using an RLC tuned resonant circuit includingcapacitor 105 to allow for more efficient signal transmission. Thecenter of bobbin 108 includes a lumen 109 to receive a lead. Anintegrated circuit 102 containing RF receiver/transmitter circuitry maybe mounted on bobbin 108. A hermetic cylindrical cover (not shown inFIG. 3) seals the transponder 262 in a manner described in U.S. Pat. No.5,782,891 to Donders, incorporated herein by reference in its entirety.FIG. 3 further illustrates a surface acoustic wave (SAW) filter 104 tofilter signals transmitted by the RF receiver/transmitter circuitry in amanner described further below.

FIG. 4 is a side perspective view illustrating a sealed transponder 262coupled to lead 14. The sealed transponder 262 may be inserted under aconnector sleeve (not shown in FIG. 4) and backfilled with medicaladhesive. It may be noted that the transponder of FIG. 3 may be coupledto the lead in many other ways. For example, in another embodiment, thetransponder may be fully integrated within the lead body instead ofbeing provided as a separate component.

FIG. 5 is a system block diagram of one embodiment of an IMD that mayutilize the current invention. IMD 300 is provided with an input/outputcircuit 320 to sense physiological signals and/or to provide electricalstimulation to a patient. If IMD 300 is a pacemaker, input/outputcircuit 320 may provide all of the basic timing, stimulation and sensingfunctions of a DDD or DDDR of a commercially-available pacing device.

Input/output circuit 320 provides the control functions of the IMD. Forexample, digital controller/timer 330, which receives a clock signalfrom crystal oscillator circuit 338, generates the appropriate timingand control sequences for the rest of the IMD. Battery 318 providespower for all the components of the IMD, and power-on-reset circuit 336defines an initial operating condition and also resets the operativestate of the device in response to detection of a low battery condition.Reference mode circuit 326 generates stable voltage and currentsreferences for the analog circuits within input/output circuit 320.

FIG. 5 also illustrates leads 14 and 15 coupled to IMD 300. Additionalleads\catheters such as exemplary lead 26 may further be implantedwithin the body for sensing signals and/or for providing electricalstimulation or drug therapy in a manner to be discussed below.

One or more of these leads may carry one or more electrodes. Lead 14,which may be an atrial bipolar pacing lead, is shown carrying twoelectrodes 19 and 21 positioned in the right atrium of heart 16.Electrodes 19 and 21 may be used both to sense and pace the atrium in amanner well known in the art. Similarly, lead 15 represents aventricular bipolar lead that may carry two electrodes 23 and 25implanted in the right ventricle of the heart 16. As discussed above inconjunction with atrial lead 14, electrodes 23 and 25 may be used tosense and pace the ventricle in a manner well known in the art.

In addition to electrodes, one or more other types of sensors of anytype known in the art for sensing physiological signals may also becarried on one or more of the leads. For example, sensors may beprovided to measure oxygen saturation, change in pressure dP/dT,temperature, minute ventilation or respiration rate. Exemplary sensorsystems are described in U.S. Pat. No. 5,154,170 to Bennett et al., U.S.Pat. No. 5,144,524 to Reuter, U.S. Pat. No. 5,271,395 to Wahlstrand, andU.S. Pat. No. 4,485,813 to Anderson.

Analog signals sensed by any of the sensors and/or electrodes may beprovided to a programmable electronic switch such as selection circuit361 to be described further below. The selected signals are provided tosense amplifiers 360. The gain of sense amplifiers 360 may be controlledvia controller/timer circuit 330 via gain/energy control 348. Theamplified analog signals are received by controller/timer circuit, andprovided to analog-to-digital converter (ADC) and multiplexor circuit328. The ADC digitizes the analog signals so that the signals may bestored and/or transferred to an external device such as a programmer.

Transmission of signals to an external device is accomplished via RFtransmitter/receiver circuit 332 and a telemetry antenna 334. The RFtransmitter/receiver circuit 332 demodulates received downlink telemetrycommunications and transmits uplink telemetry data. An exemplary circuitfor demodulating and decoding downlink telemetry may correspond to thatdisclosed in U.S. Pat. No. 4,556,063, while uplink telemetry functionsmay be provided according to U.S. Pat. Nos. 5,127,404 and 4,374,382.Uplink telemetry capabilities will typically include the ability totransmit stored digital information as well as physiological signalssensed in real-time as described in the '404 patent. It may also becapable of transmitting marker signals indicating the occurrence ofsensed and paced depolarizations in the atrium and ventricle, asdisclosed in the cited '382 patent.

IMD 300 further includes a microcomputer circuit 302. This circuitcontrols the operational functions of digital controller/timer circuit330 via data and control bus 306 by specifying, for example, whichtiming intervals are employed for performing pacing and sensingfunctions. Microcomputer 302 may include a microprocessor 304 andassociated system clock 308 and on-board processor RAM and ROM 310 and312, respectively. In addition, microcomputer circuit 302 may include anadditional storage unit such as RAM/ROM circuit 314 to provideadditional memory capacity. Microprocessor 304 may be interrupt driven,operating in a reduced power consumption mode normally, and awakened inresponse to defined interrupt events, which may include sensedphysiological signals.

In addition to interfacing to microcomputer 302, controller/timer 330further interfaces directly or indirectly with a battery 318, anactivity sensor 30, a telemetry antenna 334, and various feedthroughs(not shown in FIG. 5) to the lead connector elements included inconnector assembly 20 discussed above. A piezoelectric crystal activitysensor 30 may be provided to generate electrical pressure wave signalsin response to sensed physical activity. The generated signal isprocessed by activity circuit 322, which, in turn, provides activitysignal 324 to digital controller/timer circuit 330. Activity circuit 322and associated activity sensor 30 may correspond to the circuit andsensor disclosed in U.S. Pat. No. 5,052,388 to Sivula et al.,incorporated herein by reference in its entirety.

IMD 300 also includes an output amplifier circuit 340 to provideelectrical stimulation to heart 16 via one or more of electrodes 23 and25 on lead 18V, as well as one or more of electrodes 19 and 21 locatedon lead 18A. In order to trigger generation of a ventricular pacing orV-PACE pulse, digital controller/timer circuit 330 generates a triggersignal on V-TRIG line 342. Similarly, in order to trigger an atrialpacing or A-PACE pulse, digital controller/timer circuit 330 generates atrigger pulse on A-TRIG line 344. The A-PACE and V-PACE pulse energiesmay be controlled in pulse width and/or amplitude by gain/energy control348 which receives a pace energy command signal from digitaltimer/controller circuit 330. The timing of pacing signals may becontrolled based on programmable rate-response features that take intoconsideration one or more measured physiological parameters as known inthe art. Digital controller/timer circuit 330 defines the pacing orescape intervals used to pace the atrium and ventricle using any of thesensing and timing mechanisms known in the art. The signals generated byoutput amplifier circuit may be provided to a programmable switch suchas selection circuit 341, which is programmed by controller/timer 330 ina manner to be discussed below.

In the current embodiment, controller/timer circuit is further showncoupled to transmitter/receiver 380, which, in turn, is coupled viaconnection 386 to RF antenna 260. This antenna transmits energy topassive transponder 262 carried on lead 14. The energy, which may beoptical, electromagnetic, or ultrasonic, for example, is used to powercircuitry within passive transponder 262 such that the transponderinitiates a data transfer operation to the transmitter/receiver 380.This transferred data may include lead and sensor identificationinformation stored by the transponder and used by IMD 12 to configurethe system in a manner to be discussed further below.

In one embodiment, transmitter/receiver 380 decodes data received fromthe transponder 262, and provides this data to digital controller/timercircuit 330 for subsequent storage in RAM/ROM unit 314. The data mayalso be transmitted to an external programmer 420 (not shown in FIG. 5)via antenna 334. Digital controller/timer circuit 330 may initiate aninterrogation of the transponder following lead implant detection viaantenna 260. Lead implant detection may be performed as described inU.S. Pat. No. 5,534,018 and 6,016,447 to Wahlstrand and Juran,respectively, incorporated herein by reference in their entireties.

It may be noted that although FIG. 5 illustrates transmitter/receivercircuit 380 as being a separate circuit as compared totransmitter/receiver 332, the two circuits may be included as a singlecircuit providing both the ability to transfer and receive data to/froman outside device, and to further receive and/or transmit data from oneor more transponders such as transponder 262.

FIG. 6 is a circuit block diagram illustrating in more detail exemplarycomponents of transponder 262 and transmitter/receiver circuit 380 ofFIG. 5. Transmitter/Receiver 380 includes an energy source 390, whichmay be an inductive circuit, or a photoelectric or piezoelectrictransducer to generate electromagnetic, ultrasonic, or optical energy,respectively, as represented by line 391. This energy is received byenergy coupler 392, which generates the current and voltage levelsneeded to power the rest of transponder 262. Transponder includes acontrol circuit 393, which is coupled to a non-volatile storage device394. The non-volatile storage device may be a switch device, or anyother type of non-volatile storage device known in the art, including aread-only memory (ROM). One or more data values indicative of devicetype, device technical information, and/or device configurationinformation may be stored in storage device 394 and read by controlcircuit 393. The control circuit 393 provides this information totransmitter/receiver 395, which transmits the data via an RF or othertype of communication to transmitter/receiver 396. This transmission isindicated by line 397.

Transmitter/Receiver 380 further includes a transmitter/receiver 396that may provide an unmodulated carrier signal to transmitter/receiver395. Transmitter/receiver 395 has a tuned resonant circuit as discussedabove for resonating at the frequency of the carrier signal tore-transmit a signal at the carrier frequency. The transmitter/receiver395 also includes means for superimposing an information signal on there-transmitted signal by modulating the carrier or harmonies of thecarrier to reflect the information stored by storage device 394. It maybe noted that in an alternative embodiment, the signal provided by thetransmitter/receiver 396 is used both as the energy source and thecarrier signal such that energy source 390 is not needed.

In one embodiment of the invention, transmitter/receiver 395 may beprogrammed with information from an external transmitter/receivercircuit at the time of manufacture. This information may include modeland serial numbers, lot numbers, expiration dates, electricalcharacteristics, labeling changes, cautions, product performanceresults, recall information, and shipping information such a freight IDsand the like. The transponder could further be programmed to storeintended therapy information, indications for use, and calibrationparameters. All, or portions of, associated technical manuals may bedownloaded to the transponder as permitted by the capacity of thestorage device.

If transponder is capable of receiving data from an external device inthe manner discussed above, data stored within the IMD may be loadedinto storage device 394. For example, storage device 394 may store thetherapy settings and/or any programmable parameters used to calibratethe IMD for a specific patient. These stored settings and parameterscould then be automatically uploaded from transponder 362 following areplacement procedure during which the patient receives a new IMD. Thissaves time, since manual intervention is not required to configure thenewly-implanted device. Other information may likewise be downloaded totransponder 362, including general patient information and healthhistory, and information associated with drug therapies that may or maynot be coordinated with the therapy provided by the IMD. In oneembodiment, a physician may store information such as threshold values,lead or other impedance values, and/or additional operational anddiagnostic information that are determined either at the time ofimplant, or during subsequent patient visits.

Returning now to FIG. 5, use of the lead identification andconfiguration information is discussed further. Information from one ormore transponders such as transponder 262 may be obtained by theinput/output circuit 320 in the manner discussed above. This informationmay be stored in memory of the IMD such as memory within microcomputercircuit 302. The data may also be transferred to an external device forstorage with patient record data. This information may be analyzed bymicrocomputer circuit 302 or an external processor to automaticallyconfigure the IMD. For example, this data can be used by the processorto adjust gain/energy control circuit 348 in a manner that controls thegains of output amplifier circuit 340 and sense amplifiers 360. Theadjustments may be based on the type of leads and sensors that aredetected in the system. According to one aspect of the system, in theevent a particular lead or sensor is not present, unused functionswithin the IMD may be placed in a low-power mode to conserve batterypower.

The ability to adjust the gain associated with a sensed signal isimportant for several reasons. Physiological sensors such as pressure,temperature, oxygen saturation, or any of the other sensors types knownin the art to measure physiological parameters often have operatingparameters that vary widely. This is a result of variable conditionsthat occur during the manufacturing process, as well as differencesassociated with materials used during production. Therefore, differentsensors of the same type may have significantly different scale factors,offsets, and gains. One way to compensate for such variability involvesperforming a test at the time of implant. A physician may test sensoroperation and calibrate the sensor to account for the variable factors.A system and method for performing this type of calibration is describedin U.S. Pat. No. 5,919,221. This type of calibration procedure may betime-consuming and error prone, however.

According to the current invention, sensors may be tested at the time ofmanufacture to determine specific operating parameters. These parametersmay then be stored in transponder storage device 394, which may becarried on the sensor lead or the sensor itself. These parameters may betransferred to an IMD in the manner discussed above for use inautomatically adjusting sensor gains to account for the sensordifferences, and may be further used to adjust and calibrate the IMDfunctions associated with the sensors. For example, sensor output couldbe calibrated if an active sensor is being utilized. Such parameters mayalso be used by a data processing system such as microcomputer 302 toadjust digital values derived from the measured sensor signals. Thiseliminates the need for human intervention.

Information gained from the transponder may also be used bycontroller/timer 330 to control selection circuits 361 and 341. Forexample, the signals provided to sense amplifiers 360 may be selected byselection circuit 361 based on the leads and/or sensors being used by aparticular system. Similarly, the signals that are driven by outputamplifier circuit 340 may be selected by selection circuit 341 based onwhether a lead or a particular electrode is available within the system,and is being used to provide therapy for a given patient. The selectioncircuits thereby provide “plug-and-play” capabilities for the IMDconnector block based on the devices that are sensed within the system.

Information provided by the transponder may further be used to selectthe configuration of switchable circuits such as those described in U.S.Pat. No. 4,665,919 to Mensink, incorporated herein by reference in itsentirety. The configuration of the switchable circuits controls one ormore operating parameters of the device, such as input amplifierparameters and filter settings and sensitivity. This configuration canbe modified based on the type of components available within the systemas indicated by data stored in one or more of transponder circuits 362.

The uses of the configuration and calibration data discussed above areexemplary only, and it will be understood that such data may be used inmany other ways to program or automatically calibrate electroniccircuitry associated with an IMD or an external device used with theIMD.

FIG. 7 is a system block diagram of additional embodiments of thepresent invention. Specifically, a bi-directional wirelesscommunications system between programmer 420, personal data management(PDM) unit 420′ and a number of implantable medical devices (IMDS)represented by IMD 410, IMD 410′ and IMD 410″ is shown. The IMDs areimplanted in patient 10 beneath the skin or muscle. The IMDs areelectrically coupled to electrodes 418, 430, and 436 respectively in amanner known in the art. IMD 410 may include a microprocessor fortiming, sensing and pacing functions consistent with preset programmedfunctions as discussed above. Similarly, IMDs 410′ and 410″ may bemicroprocessor-based to provide timing and sensing functions to executethe clinical functions for which they are employed. For example, IMD410′ could provide neural stimulation to the brain via electrode 430 andIMD 410″, and/or may function as a drug delivery system that iscontrolled by electrode 436.

The various functions of the IMDs may be coordinated using wirelesstelemetry. Wireless links 442, 444 and 446 jointly and severally coupleIMDs 410, 410′ and 410″ such that programmer 420 may transmit commandsor data to any or all the of IMDs via one of telemetry antennas 428, 432and 438. This configuration provides a highly flexible and economicalwireless communications system between the IMDS. Further, the structureprovides a redundant communications system, which enables access to anyone of a multiplicity of IMDs in the event of a malfunction of one ortwo of antennas 428, 432 and 438.

Programming commands or data are transmitted from programmer 420 to IMDs410, 410′ and 410″ via external RF telemetry antenna 424. Telemetryantenna 424 may be an RF head or equivalent. Antenna 424 may be locatedon programmer 420 externally on the case or housing. Telemetry antenna424 is generally telescoping and may be adjustable on the case ofprogrammer 420. Both programmer 420 and PDM unit 420′ may be placed afew feet away from patient 10 and would still be within range towirelessly communicate with telemetry antennas 428, 432 and 438.

In one embodiment, a remote web-based expert data center 462 may beaccomplished through programmer 420 or PDM unit 420′. Accordingly,programmer 420 and PDM unit 420′ function as an interface between IMDs410, 410′ and 410″ and data center 462. One of the many distinguishingelements of the present invention includes the use of various scalable,reliable and high-speed wireless communication systems tobi-directionally transmit high fidelity digital/analog data betweenprogrammer 420 and data center 462.

There are a variety of wireless mediums through which datacommunications could be established between programmer 420 or PDM unit420′ and data center 462. The communications link between programmer 420or PDM unit 420′ and data center 462 could be modem 460, which isconnected both to programmer 420 and to data center 462.

Alternative data transmission systems include, without limitations,stationary microwave and/or RF antennas 448 being wirelessly connectedto programmer 420 via tunable frequency wave 450, and with data center462 via wireless link 465. Similarly, PDM unit 420′, mobile vehicle 452,and satellite 456 are in communications with data center 462 via similarwireless links. Further, mobile system 452 and satellite 456 are inwireless communications with programmer 420 or PDM unit 420′ via tunablefrequency waves 454 and 458, respectively.

In one embodiment, a telnet system may be used to wirelessly access datacenter 462. Telnet emulates a client/server model and requires that theclient run dedicated software to access data center 462. The telnetscheme may employ various operating systems including UNIX, Macintosh,and all versions of Windows.

Using the system shown in FIG. 6, an operator at programmer 420 or datacenter 462 may initiate remote contact with any of the implanted devicesvia link antennas 428, 432 and 438 to enable data reception andtransmission. For example, an operator or a clinician at data center 462may downlink to programmer 420 to perform a routine evaluation ofprogrammer 420. If a downlink is required from programmer 420 to IMD 410for example, the downlink is affected using telemetry antenna 422. Inthe alternate, if an uplink is initiated from patient 10 to programmer420, the uplink is executed via wireless link 426.

Each antenna from the IMDs can be used to uplink all or one of the IMDsto programmer 420. For example, IMD 410″, which relates to neuralimplant 430, can be implemented to up-link, via wireless antenna 434 orwireless antenna 434′, any one, two or more IMDs to programmer 420.Preferably bluetooth or equivalent chips, adopted to function within abody and which result in low current drain, are included in the IMD toprovide wireless and seamless connections 442, 444 and 446 between IMDs410, 410′ and 410″. The communication scheme is designed to be broadbandcompatible and capable of simultaneously supporting multiple informationsets and architecture, transmitting at relatively high speed, to providedata, sound and video services on demand.

The various communication paths as shown in FIG. 6 allow leadidentification and sensor configuration data to be uploaded to eitherprogrammer 420, or to data center 462. Specifically, in the system ofFIG. 6, a transmitter/receiver such as transmitter/receiver 380 (FIG. 5)may be resident in programmer 420. This transmitter/receiver mayinterrogate transponders provided on one or more of the leads todetermine lead types, serial numbers, and any available sensorcalibration values in a manner similar to that described above. Thetransfer of information from the transponders may be performed usingdata encryption technology as described in the co-pending applicationentitled “Method and Apparatus to Secure Data Transfer from MedicalDevice Systems”, Ser. No. 09/431,881 filed Nov. 2, 1999 by Nichols andincorporated herein by reference. Information that is gained during theinterrogation may be entered and stored into a patient record eitherwithin the memory of programmer 420, or at data center 462. Theinformation may further be employed to configure one or more IMDfunctions or systems automatically based on lead types, and/or may alsobe used to calibrate sensor circuits in ways similar to those discussedabove.

In yet another embodiment, a transmitter/receiver such astransmitter/receiver 380 (FIG. 5) may instead be resident in PDM 420′.This transmitter/receiver may interrogate all lead componentsinterconnected to the various IMDs to determine lead types, serialnumbers, any sensor calibration values, and to communicate thisinformation to programmer 420. Programmer may then program any or all ofthe IMDs to properly configure the IMD configurations. Alternatively,this configuration function may be performed by the processing circuitassociated with each IMD.

The foregoing examples describe several embodiments of the inventiverecognition and configuration system and method, although it will beunderstood that modifications are possible within the scope of thecurrent invention. For example, the foregoing examples discuss a systemthat is powered using a remote energy source and an energy coupler asshown in FIG. 6. Other types of power systems may be utilized, however.In one instance, transponder 262 is not passive, but instead receivespower by loosely coupling off of electrical therapy output of an IMD.

FIG. 8 is a circuit diagram illustrating a transponder 498 coupled tothe therapy output energy source of IMD 500. IMD 500 is shown coupled toa lead that includes two conductors 504 and 506. These conductors arecoupled to a bridge circuit that includes capacitor 508. This capacitoris charged by one or more pulse signals generated by IMD 500 during, forexample, the delivery of pacing therapies or other pulsed stimulationtherapies. The pulsed signals 509 include a position and a negativephase such that during a portion of the signal, the voltage at point 510is more position than at point 512, and in a different portion of thesignal, the voltage polarity is reverse. In the former instance, currentflows through diodes 514 and 516, and in the later instance currentflows through diodes 518 and 520. In both cases, capacitor 510 ischarged in the manner shown.

In the preferred embodiment, capacitor 510 is charged by the occurrenceof multiple pulsed signals. For example, ten or more pulses may berequired to completely charge the capacitor. The values of resistors 522and 524 are selected to prevent the capacitor circuit from presenting anunduly large load that would affect the therapy delivery of IMD 500.Capacitors 526 and 528 may be provided to prevent a DC offset voltagepotential from being present across conductors 504 and 506, which maypromote corrosion of any electrodes that are carried by the lead.Finally, it may be noted that if a unipolar lead is employed, thecapacitor circuit is coupled to only a single lead conductor, with thesecond connection being provided via the IMD and transponder cans, asindicated by dashed line 530.

Using the circuit of FIG. 8, transponder 498 may be intermittentlyoperated to provide a brief burst of modulated RF energy from thetransmitter of the transponder. In a similar manner, the receiver of thetransponder could be intermittently powered to receive information fromthe IMD or another source. This embodiment would allow for longer-rangecommunications than is provided by the passively-powered embodiment.

Another modification to the current invention involves use of a surfaceacoustic wave (SAW) filter 104 within the transponder as shown in FIG.3. This type of filter includes an SAW delay line. An RF signal istransmitted from an interrogation unit such as transmitter/receivercircuit 380 of FIG. 6, and is received by an antenna residing in thetransponder that is coupled to the delay line. The signal is provided tothe delay line, which includes predetermined discontinuities that resultin signal reflections. The unique signal reflections, which are a resultof the selected configuration of the delay line, can be interpreted as asignature which may be transmitted to the interrogation unit forinterpretation. The signature may encode a serial number, or any othertype of information. The SAW filter thereby serves as a nonvolatilestorage device not unlike a bard-wired switch. This filter may be usedin place of, or in addition to, storage devices such as storage device394 of FIG. 6.

According to another aspect of the invention, data stored within atransponder 362 of a component is employed by an IMD to configurecircuitry within the component. For example, an embodiment of a lead mayinclude data interface to couple to an interface of the IMD. Based oninformation transferred from a transponder of the lead to the IMD, aprocessing circuit such as micro-computer circuit 302 is capable oftransferring signals via the data interface to configure circuitry ofthe lead. For example, the processing circuit may store data within aprogrammable device such as a register provided by the lead, therebyconfiguring the lead for operation with the IMD.

Other modifications are possible within the scope of the currentinvention. For example, although the above-described embodimentsprimarily relate to a transponder attached to, or integrated within, alead, the invention may be usefully employed to identify otherimplantable medical devices that may be used in conjunction with theactive IMD in the system. For example, pluggable antennas or electrodesthat may be selectively coupled to the active IMD may be identified andconfigured using a mechanism similar to that described herein.Additional components such as heart valves or stents could includesimilar transponders on the surface of, or integrated within, the deviceto store information that may then be transferred to external devicesthat are located within, or outside of, the body. Therefore, whileparticular embodiments of the present invention have been disclosed, itis to be understood that various different modifications are possibleand are contemplated within the scope of the specification, drawings,abstract and appended claims.

What is claimed is:
 1. A system to configure an implantable medicaldevice (IMD), comprising: an IMD; at least one additional componentadapted to be coupled to the IMD; the at least one additional componentcomprising a stimulating electrode; a data set descriptive of the atleast one additional component; the data set comprising data descriptiveof the stimulating electrode; a first communication circuit carried onthe at least one additional component, the first communication circuitcomprising means to store and transmit the data set; a secondcommunication circuit in proximity to the first communication circuitcomprising means to receive the data set from the first communicationcircuit; and a processing circuit coupled to receive the data set fromthe second communication circuit, and to configure initial operations ofthe IMD based on the data set.
 2. The system of claim 1, wherein thefirst communication circuit is a transponder.
 3. The system of claim 2,wherein the transponder is a passive transponder.
 4. The system of claim1, wherein the data set further comprises data indicative of componentidentification information.
 5. The system of claim 1, wherein the dataset further comprises data included in a technical manual associatedwith the at least one additional component.
 6. The system of claim 1,wherein the at least one additional component further comprises a sensorto sense a physiological parameter, and wherein the data set furthercomprises data descriptive of the sensor.
 7. The system of claim 6,wherein the system further includes means for calibrating the sensorbased on the data descriptive of the sensor.
 8. The system of claim 1,wherein the at least one additional component further comprises aconnector adapted to be coupled to the IMD, and wherein the data setfurther comprises data descriptive of the connector.
 9. The system ofclaim 1, wherein the second communication circuit is located within theIMD.
 10. The system of claim 1, further comprising an external deviceand wherein the second communication circuit is located in the externaldevice.
 11. The system of claim 10, wherein the external devicecomprises a programmer.
 12. The system of claim 10, wherein the externaldevice comprises a patient data module (PDM).
 13. The system of claim 1,wherein the means to transmit the data set of the first communicationcircuit includes an RF transmitter.
 14. The system of claim 1, whereinthe second communications circuit further comprises means fortransmitting information and the first communication circuit furthercomprises an RF receiver capable of receiving the information from thesecond communication circuit.
 15. The system of claim 14, the firstcommunication circuit further comprises means to store the informationreceived from the second communication circuit.
 16. The system of claim1, wherein the first communication circuit further comprises means forfiltering a signal containing the data set, the filtering meansincluding a surface acoustic wave (SAW) filter.
 17. The system of claim1, wherein the IMD includes at least one amplification circuit, andwherein the system further includes a gain adjustment circuit coupled tocontrol the gain of the at least one amplification circuit, and whereinthe processing circuit is capable of configuring the gain adjustmentcircuit based on the data set.
 18. The system of claim 1, wherein thesystem further includes at least one selection circuit coupled to the atleast one additional component, and wherein the processing circuit iscapable of configuring the selection circuit to control interconnectionof the at least one additional component with the IMD based on the dataset.